Immunogenicity and safety in newborns of a new recombinant hepatitis B vaccine containing the S and pre-S2 antigens

Abstract

A study to evaluate the safety and immunogenicity of a recombinant hepatitis B vaccine containing the S and pre-S2 antigens (GenHevac B Pasteur) was conducted in healthy newborn infants. All infants received 20 μg of vaccine within 24 h of birth and at 1 and 2 months with a booster injection at month 12. The vaccine was administered alone in 19 infants born to low risk mothers, i.e. surface antigen (HBsAg)-negative and antibody to the core antigen (Anti-HBc)-positive mothers. The vaccine was administered in combination with 100 IU hepatitis B immune globulin (HBIg) at birth and 1 month in 18 infants born to high risk mothers, i.e. HBsAg positive mothers. In the group not receiving HBIg, the anti-HBs seroconversion rate at the 10 mIU ml −1 threshold was 50% 1 month after the first injection. In both groups, the anti-HBs seroconversion rates were 100% 1 month after the third injection and > 85% 1 month after the second injection. After the booster injection > 90% of the infants had an anti-HBs titre > 1000 mIU ml −1 which will probably provide them with adequate protection for several years. The kinetics of the anti-pre-S2 response was similar to that of the anti-HBs response and 100% of infants in both groups had seroconverted 1 month after the second injection of the vaccine. The side effects were scarce, all mild and transient. Given the protective role of the anti-pre-S2 antibodies, the precocity of the response to pre-S2 antigen may therefore increase the effectiveness of hepatitis vaccination. We conclude that GenHevac B vaccine is highly immunogenic and safe for use in newborn infants, alone or in combination with HBIg.